Papermaking machine



Jan. 30, 1962 F. B. LO PPNOW 3,018,757

PAPERMAKING MACHINE Filed June 1. 1959 4 Sheets-Sheet 1 Jan. 30, 1962 F. B. LOPPNOW PAPERMAKING MACHINE 4 Sheets-Sheet 2 Filed June 1. 1959 Jan. 30, 1962 F. B. LOPPNOW PAPERMAKING MACHINE 4 Sheets-Sheet 3 Filed June 1, 1959 Jan. 30, 1962 F. B. LOPPNOW 3,018,757

PAPERMAKING MACHINE Filed June 1, 1959 4 Sheets-Sheet 4 PRIOR ART 3,fll8,757' Patented Jan. 30, 1962 3,013,757 PAPERMAKING MACHINE Frank B. Loppnow, Appleton, Wis, assignor to Kimberly- Clark Corporation, Neenah, Wis., a corporation of Delaware Filed June 1, 1959, Ser. No. 817,221 8 Claims. (Cl. 118262) This invention relates to paper coating machines and particularly to mechanism for reducing turbulence and splashing in coating ponds of these machines when the machines are operated at high speeds.

Paper coating machines of a Well known type may cornpnise a train of two or more rotating rolls which act to transfer a uniform, metered film of coating to an applicator roll, which in turn applies a film of coating to a paper web. The liquid coating, which may be of a conventional mineral-adhesive type, is supplied from a pond of coating material maintained in a nip formed by a metering roll and a backup roll included in the roll tr-ain. During operation this pond of coating, encompassed by the metering and backup rolls, eventually becomes violently agitated as the speed of rotation of the rolls increases. To prevent splashing of globules of the fluid coating onto the applicator roll or some other intermediate rolls of the roll train, disrupting the uniformity of the film. supplied to the applicator roll and thus to the web, prior constructions have provided a partition or splash guard of some stifl material, such as heavy canvas interposed on that edge of the coating pond which is more adjacent the applicator roll. The partition extends downwardly almost touching the surface of the metering roll and acts to intercept such globules of coating. The splash guard, however, does not reduce the splashing and turbulence present in the coating pond, and the consequent entrainment of large quantities of air by the coating. Such entrainment changes the physical properties of the coating, including the metering properties, and results in a non-uniform coating. Extreme cases of entrainment produce coatings displaying a crater-like appearance under high magnification. Entrainment of air in the coating also results in a progressive loss of viscosity by the coating causing the coating to be increasingly responsive to the agitation induced by the rotating rolls, the agitation eventually expelling splashes of coating from the pond in all directions and possibly reducing the coating in the pond to a point where a portion of the nip may not be adequately supplied with coating.

It is, therefore, an object of the present invention to minimize the turbulence and splashing ordinarily encountered in the reservoir of liquid coating during high speed operation with a coater of the above mentioned type.

It is a further object of the invention to decrease the quantity of air entrained by the liquid coating by reducing such turbulence and splashing, thus maintaining the coating at a uniform viscosity and insuring eflicicnt operation and a high grade of product.

More particularly, it is an object of the invention to introduce a coating deflector into the coating pond for l the purpose of hydraulically stabilizing the pond. It is contemplated that with the improved mechanism of the t present invention, a roll coater can operate at consideralbly higher speeds than heretofore possible with existing 1 construction-s.

Briefly, my improved mechanism for reducing turbullence and minimizing splashing may comprise, in a preferred form, a rigid coating deflector extending downwardly into the coating nip adjacent the metering roll and conforming to the curvature of the metering roll.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects, and such other objects, as Will be apparent from the following description of a preferred form of the invention, illustrated with reference to the accompanying drawings, wherein:

FIGURE 1 is a side elevational view of a paper coating press embodying principles of the present invention;

FIGURE 2 is a sectional view taken along line 22 of FIGURE 1;

FIGURE 3 is a sectional view on an enlarged scale taken along line 33 of FIGURE 2; and

FIGURE 4 is a view similarto FIGURE 3 of a prior art structure.

Like characters of reference designate like pants in the several views.

Referring now to FIGURE 1, the illustrated coating press includes a backing roll 10, an applicator roll 11, a transfer roll 12, a metering roll 13, and a backup roll 14 rotatably mounted on a frame 15 and spaced so that a nip is formed at the line of contact between neighboring rolls. Rolls 10, 11, 12 and 14 may be rubber covered, while roll 13 is preferably a chrome plated steel roll.

A pond of liquid coating 16 is provided in the nip formed by the metering roll 13 and the backup roll 14. A coating inlet pipe 17 extends laterally with respect to the rolls and is positioned above the pond of coating 16 as seen in FIGURES 2 and 3. A manifold pipe 18 supplied with multiple outlets 19 lies beneath the inlet pipe 17, and the two pipes are joined by a vertical connecting pipe 20. A coating supply 21 is connected to the coating inlet pipe 17, supplying coating from the left in the pipe 17 as seen in FIGURE 2, and the right end of the pipe 17 is partitioned off internally so that it simply act-s as a support.

Sheet metal shrouds 22 are attached in any suitable manner to the sides of the pipes 17 and 18, and the pipeshroud structure is suspended over the pond 1 6 by means of support brackets 23 anchored to the frame 15.

A sheet metal guard holder 24 is coextensive transversely of the machine with a shroud 22 to which the holder 24 is rigidly attached, and a guard 25 of hard rubber or other rigid material is attached to the holder 24, so that the lower edge of the guard 25 is in close proximity to the surface of the metering roll 13.

A coating deflector baflle 26 of some thin sheet material, preferably stainless steel, is attached in any suitable manner to one side of the holder 24. The arcuate portion 27 of the coating deflector 26 is shaped to concentrically conform to the surface of the metering roll 13, and the portion 27 extends downwardly into the coating pond 16 and so positioned as to provide a substantial clearance above the nip formed by the rolls 13 and 14.

In the operation of the coating press described above, the backing roll 10, the applicator roll 11, the transfer roll 12, the metering roll 13, and the backup roll 14 are mounted on the frame 15; and one or more of the rolls is driven by driving mechanism such as by driving motors 10a, 11a, 12a, 13a and 14a for the rolls 10, 11, 12, 13 and 14, respectively, shown schematically in FIG. 1, so that each of the rolls rotates counter-directionally with respect to the roll or rolls with which it is in contact.

Liquid coating of suitable composition and viscosity flows from the source of supply 21 and passes through the inlet pipe 17 and the connecting pipe 20 into the manifold pipe 18, and thence is uniformly distributed from the multiple outlets 19 to form the coating pond 16 between the metering roll 13 and the backup roll 14.

As seen in FIGURE 3, the metering roll 13 is driven in the clockwise direction and the backup roll 14 is driven in the counter-clockwise direction. The peripheral surfaces of the metering roll 13 and the backup roll 14 move in convergent paths above the nip and describe, and are in contact with, the coating pond. A quantity of coating adheres to the surfaces of the rolls 13 and 14 as they pass through the nip between the rolls; and as these rolls continue to rotate, the peripheral surfaces below the nip diverge to split the coating, leaving a thin, well distributed film adhering to the surface of each of the rolls 13 and 14. As the metering roll 13 continues to revolve, the thin layer of coating on its surface is carried to the nip between the rolls 12 and 13, where a further coating split is effected, leaving on the surface of the transfer roll 12, a portion of the coating which is smoother and more even ly distributed than that coating carried to the nip by the roll 13. Roll 12 rotates in contact with the applicator roll 11 and transfers thereon, by similar action, a further divided portion of coating film, which film in turn is split by the roll 11 acting on the paper web 28 to deposit a highly uniform coating on the web 28 as it passes beyond the nip formed by the rolls and 11 in the direction indicated in FIGURE 1.

During operation at web (roll surface) speeds of 200 to 500 feet per minute, the coating pond 16 is substantially placid when coatings of a suitable viscosity are employed. As the speed of operation increases, however, the coating in the pond 16 becomes agitated, and the present invention resides in the attachment to the guard holder 24 of a coating deflector 26, the arcuate portion 27 of which extends downwardly into the coating pond 16, to minimize any turbulence and splashing tending to occur in the coating pond 16 at the higher operational speeds. Experience has proven that the arcuate portion 27 of the coating deflector 26 should preferably conform to and be stationed adjacent the smaller metering roll 13 and at a distance from the roll in excess of one-tenth of the radius of the roll 13, permitting some flow of coating between the arcuate portion 27 and the roll 13, and that the bottom edge of the arcuate portion 27 should not extend downwardly into the pond 16 substantially more than two-fifths of the distance from the top of the metering roll 13 to the center of the nip between the rolls 13 and 14.

The rolls 13 and 14 operating at high speeds generate currents, shown by the arrows 29 in FIGURE 3, originating adjacent the roll surfaces at the sides of the coating pond 16. Those coating currents adjacent the surface of the metering roll 13, which is considerably smaller in diameter than the backup roll 14, are somewhat more swift and are directed more laterally than the currents adjacent the roll '14 due to the different roll diameters. These swifter currents 29 adjacent the smaller metering roll 13 are reduced in effect by being shielded from the main body of the coating 16 between the rolls 13 and 14 by the arcuate portion 27 in close proximity to the roll 13. As for the currents generated by the backup roll 14; in travelling through the pond 16, these currents encounter the arcuate portion 27 and are deflected so as to largely isolate the currents 29 generated by the roll 13 from the currents generated by the roll 14. Where these currents do come together, below the end of the arcuate portion 27, they initiate an orderly rolling motion of coating in the pond as shown by the arrows 30 and thus minimize splashing and turbulence within the pond 13.

Any small splashes of coating that may occur between the metering roll 13 and the arcuate portion 27 are prevented from travelling in the direction of the applicator roll 11 by the guard 25.

FIGURE 4 shows' the conditions that exist using prior art constructions and has been included for the purpose of contrasting the present invention with such prior constructions. The splash guard 31, normally fabricated of heavy canvas or some other semi-rigid material, is positioned with its lower edge close to the surface of the metering roll 13, but substantially above the surface of the pond 16, and is provided solely for the purpose of intercepting any splashes of coating moving in the direction of the applicator roll 11. Currents, as shown by arrows 32, are generated adjacent the rotating rolls 13 and 14, and since they are not defiected, theyreverse and combine to form reinforced upward currents, shown by arrows 33, which eventually produce splashes 34 of coating. The turbulence and splashing mounts rapidly as the rotational speeds of the rollsincrease, and eventually a speed is reached at which thecoating press no longer can be operated satisfactorily, both because entrained air has impaired the uniformity of the coated product and because the pond may be so agitated that sufficient coating may not be available to all portions of the nip.

My invention is a simple and inexpensive addition to available coating press equipment permitting the production of a uniform product at considerably higher rates of operation than heretofore practicable. The problems of air entrainment in the coating and splashing of the coating are greatly reduced, contributing to improved cleanliness of operation and increased efficiency.

I wish it to be understood that the invention is not to be limited to the specific constructions and arrangements shown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

I claim:

1. A device for coating a web of sheet material comprising a pair of rotatable rolls having a nip between them for confining a pond of coating liquid, means for driving said rolls in counter-rotation, means for transferring coating from one of said rolls to a web of sheet material, and a coating deflector baffle extending downwardly toward said nip and into and below the surface of said pond for minimizing turbulence in the pond of coating as said rolls rotate.

2. A device for coating a paper web comprising a pair of rotatable rolls having a nip between them for confining a pond of coating liquid, means for driving said rolls in counter-rotation, means for transferring coating from one of said rolls to a paper web, a splash guard positioned in close proximity to said last mentioned roll so as to be interposed between said pond of coating liquid and said web of paper, and a coating deflector baffle extending downwardly toward said nip and into and below the surface of said pond for minimizing turbulence in the pond of coating as said rolls rotate.

3. A device for coating a paper web comprising a pair of rotatable rolls having a nip between them for confining a pond of coating liquid, means for driving said rolls in counter-rotation, means for transferring coating from one of said rolls to said paper web, and a coating deflector bafi'le extending downwardly toward said nip and into and below the surface of said pond and having a lower arcuately shaped portion concentrically conforming to and adjacent to one of said pond confining rolls for the purpose of minimizing turbulence and splashing in the pond of coating as the rolls rotate.

4. A device for coating a paper web comprising a pair of rotatable rolls of unequal size having a nip therebetween for confining a pond of coating liquid, means for driving said rolls in counter-rotation, means for transferring coating from the smaller of said rolls to said web of paper and a coating deflector baflle extending downwardly toward said nip and into and below the surface of said pond and having a lower arcuately shaped portion concentrically conforming to and adjacent to the periphery of the smaller of said pond confining rolls for the purpose of minimizing turbulence and splashing in the pond as the rolls rotate.

5. A device for coating a paper web comprising a pair of rotatable rolls of unequal diameter having a nip between them for confining a pond of coating, means for driving said rolls in counter-rotation, a coating inlet pipe adapted to be connected to a supply of coating, a manifold pipe connected to receive coating from said inlet pipe and having a plurality of outlets for distributing the coating across said pond, a coating applicator roll and a backup roll having a nip between them and being adapted to pass the paper web between them and through the nip, means for transferring coating to said applicator roll from the smaller of said pond confining rolls and including a transfer roll in contact with one of these rolls, a splash guard positioned in close proximity to said smaller roll so as to be interposed between said pond of coating liquid and said web of paper, and a coating deflector bafiie extending downwardly toward said first named nip and into and below the surface of said pond and having a lower arcuately shaped portion concentrically conforming to and adjacent to the periphery of said smaller roll for the purpose of minimizing turbulence and splashing in the pond as the rolls rotate.

6. A device for coating a web of sheet material comprising a pair of rotatable rolls having a nip between them for confining a pond of coating liquid, means for driving said rolls in counter-rotation, means for transferring coating from one of said rolls to the web of sheet material, and a coating deflector baffle extending downwardly toward said nip and being located adjacent one of said rolls but at a distance from the roll in excess of one-tenth of the radius of the roll and into and below the surface of the pond for minimizing turbulence in the pond of coating as said rolls rotate.

7. A device for coating a web of sheet material comprising a pair of rotatable rolls having a nip between them for confining a pond of coating liquid, means for driving said rolls in counter-rotation, means for transferring coating from one of said rolls to the web of sheet material, and a coating deflector baffle extending toward said nip not more than two-fifths of the distance from the top of one of the rolls to the center of said nip so as to extend below the surface of the pond and being located adjacent said last named roll and extending about the peripheral surface of said last named roll but at a distance in excess of one-tenth the radius of said last named roll.

8. A device for coating :1 paper web comprising a pair of rotatable rolls of unequal size having a nip between them for confining a pond of coating liquid, means for driving said rolls in counter-rotation, means for transferring coating from the smaller of said rolls to the paper web, a splash guard positioned in close proximity to said smaller roll so as to be interposed between said pond of coating liquid and the web of paper, a stationary support extending lengthwise of said rolls for holding said splash guard, and a coating deflector baffie held by said support and extending close to but spaced from the surface of said smaller roll and downwardly toward said nip and into and below the surface of the pond for minimizing turbulence in the pond as said rolls rotate.

References Cited in the file of this patent UNITED STATES PATENTS 1,918,418 Munch July 18, 1933 1,989,036 Bradner Jan. 22, 1935 2,676,563 Montgomery et al. Apr. 27, 1954 2,855,895 Burns et al. Oct. 14, 1958 

